1. Field of the Invention
This invention relates in general to modular electronic circuit devices and more particularly to a device for mounting electrical substrates to a carrier substrate.
2. Background Art
In the past few years, the use of plug-in units for electrical components has found favor within the electronics industry. Such plug-in units generally comprise a structure upon which are mounted electrical assemblies or sub-assemblies, the structure being arranged to be plugged in a suitable socket provided on a base chassis. When so plugged the components carried by the plug-in unit are electrically connected in proper circuit relation to other electrical equipment carried by the base chassis.
Recently, however, with the coming of film circuits, the need for a specialized carrier structure for housing the sub-assembly has disappeared. This is mainly due to the smaller size of a film circuit. Compared to a circuit fashioned of discrete components, the film circuit is appreciably smaller and lighter. It is not uncommon to have film circuits plugged directly into larger circuit cards or other carrier substrates and in turn the larger substrate plugged into the base chassis. At present, most installations of film circuits to circuit cards are done as permanent installations. Therefore, removal and replacement of the film circuits though not impossible, is a tedious and labor intensive job.
One solution to the problem set forth above is embodied in my U.S. Pat. No. 4,821,149 which issued on Apr. 11, 1989. A lower substrate is in this arrangement a carrier substrate incorporate a card guide facilitating the dropping of a flanged or keyed substrate directly onto the carrier substrate as an aid in assembling.
In the arrangement taught therein, the electrical substrate is manually inserted between two guides included on the carrier substrate and pushed forward between the guides. The forward tabs on the electrical substrate are longer than the rear slots, thus riding over the rear slots during insertion. The substrate is installed further between the guides after which the electrical substrate tabs become keyed in slots in the sides of the guides. Angled surfaces of the slots facilitate the substrate sliding further down onto lower shelf portions of the guides as the electrical substrate is urged forward and in a downward direction. One suggested improvement includes the provision of slotted card guides so that the electrical substrate could be mounted directly from the top of the guides on the carrier substrate. To facilitate factory assembly, however, it was determined while this eliminated the need of inserting the electrical substrate from the end as taught in my prior patent the proposed arrangement if utilized in field sites where the substrate would be removed from the handle end of the guide, the substrate might be found to enter the openings on top of the guides and subsequently the electrical substrate might fall into an adjoining substrate. Accordingly, it is the object of the present invention to disclose a new structure for mounting electrical substrates onto carrier substrates which eliminates some of the problems discovered in connection with previous solutions to the problem.